Custom Paths in attachment_fu

If you’ve used attachment_fu (introduction here) in your Rails applications, you probably love its simple nature and its S3 integration. You may love less its very sparse documentation. When working on a project recently, I needed to save items to a path based on the owner of the attachment model, not the model itself.

The first attempt involved adding inline instance method calls to the :path_prefix option passed into has_attachment. This failed because has_attachment works on the class level, not the instance level.

After digging deeper, I found that the only thing one needs to do in order to change the path of a save in attachment_fu is to have a defined base_path method in your model. In the example of a user-based system with an avatar stored for each user, this might be a useful way to define your base_path:

class Avatar  :image,                 :storage => :s3,                 :resize_to => '150x150'  				   	    def after_save      # Delete any existing avatars they have uploaded.      Avatar.find(:all, :conditions => ["user_id = ?",self.user_id]).each do |ava|        ava.destroy unless ==      end    end          # Here we define base_path and therefore save to a custom location    def base_path      File.join("users", self.user.login, "avatar")    end  	    validates_as_attachment  end

This is a very simple example, but this provides a model of an avatar that will save to a folder under users/theusername with the filename the same as . For even further customization (including the filename), dig into the full_filename method in your storage solution of choice, and override in a similar fashion.

Just a quick Rails tip to help you along your attaching way.